Hydraulic elevators



April 25. 1961 J. H. BORDEN HYDRAULIC ELEvAToRs 5 Sheets-Sheet 1 FiledAug. l2, 1959 JNVENTOR.

JOSEPH H. BORDEN BY 1 ywwwww ATTORN Ys l April 25, 1961 J. H. BORDEN2,981,375

HYDRAULIC ELEVATORS med Aug. 12, 1959 5 sheets-sheet 2 INVENTOR.

JOSEPH H. BORDEN BY ATTO NEYS April 25, 1961 J. H. BORDEN 2,981,375

HYDRAULIC ELEVATORS Filed Aug. 12, 1959 5 Sheets-Sheet 5 JNVENTOR.

JOSEPH H. BORDEN ATTOR YS April 25, 1961 .1. H. BORDEN 2,981,375

HYDRAULIC ELEVATORS Filed Aug. 12, 1959 5 Sheets-Sheet 4 JOSEPH H.BORDEN ATTOR April 25, 1961 J. H. BoRDl-:N 2,981,375

HYDRAULIC ELEvAToRs JOSEPH H. BORDEN i ATTEEYS 7 2,981,375 Patented Apr.25, 1961 HYDRAULIC ELEVATGRS Joseph H. Borden, Toledo, Ohio, assignor toToledo Scale Corporation, Toledo, Ohio, a corporation of Ohio Filed Aug.12, 1959, tSer. No. 833,203

38 Claims. (-Cl. IS7-28) This invention relates to hydraulic elevators.

Hydraulic elevators are particularly well suited for hauling freight andhave certain advantages especially for low rise installations. However,heretofore, such elevators have been generally unsatisfactory in certainaspects. Many prior hydraulic elevators have two motor operated pumpseach of a different capacity for slow, fast and intermediate speeds,even though it is desirable, from the standpoint of cost, simplicity ofoper-ation, and optimum acceleration and deceleration, to operate such asystem with only a single motor operated pump and with an inlinitenumber of speeds for any one load for smooth acceleration anddeceleration. The prior hydraulic elevators -a'lso are unsatisfactory inthat they do not provide by simple means `a uniform leveling speed and auniform top or running speed for various loadings. None of the priorhydraulic elevators have a really satisfactory method for leveling thecars at landings. Furthermore, all of the prior hydraulic elevatorsystems are relatively complicated and bulky.

It is, accordingly, the principal object of this invention to provide animproved hydraulic elevator.

Another object of the invention is to provide a simplified hydrauliccontrol system for an elevator.

A further object of the invention -is to provide, for an elevator, ahydraulic system which has an infinite number of speeds for any one loadfor smooth acceleration and deceleration.

Still another object is to provide, vfor an elevator, a hydraulic systemwhich has a uniform leveling speed and a uniform top or running speedfor variousfloadings.

Another object is to provide, for an elevator, a hydraulic system havingimproved meansfor leveling ya car at a,` landing. ,t Y

A still further objectl is to provide, for an elevator, a hydraulicsystem which `is exceedingly compact, easy. -to

operate, of low cost and, which istrouble free. ,v Tl1eseand-otherobjects and advantages are apparent from the `following descriptionofthe invention.- 4

According to the invention, the .hydraulic,elevatornin-` cludes a singlemotor operated pump-in aline connected `to atcylinder having a pistonthat' raises" and lowersan. elevator car.

tive for lifting the elevator car, the car starts up slowly at levelingspeed, but accelerates to top speed asthe control valve slowly closes.The other by-pass and its dashpot connected control valve, i.e., thedown control valve, is isolated from the system during the up travel bymeans of a fully closed on or off stop valve. As the car approaches theselected landing, the up control valve opens slowly to decelerate thecar to leveling speed and when the car is level with the landing thepump is stopped to stop the car. This simple arrangement of a dashpotoperated valve in a by-pass provides a smooth acceleration anddeceleration in the up direction and in Combination with the downcontrol valve together with its by-pass provides a system which isoperable with only one pump.

Should the car settle slightly, the pump is started to raise the Vcar atleveling speedthis arrangement being another feature of the system.

Upon the registration of a down start signal, the down control valvewhich is normally closed starts to open slowly and the stop valve whichis in series with the down control valve opens fully. During down travelthepump is not operated. 'Ille car starts down slowly at' levelingyspeed under the influence of gravity, but accelerates as thevcontrolvalve slowly opens. The up control valve together withV its by-pass isisolated from the system during the down travel by means of a checkvalve. As

the car approaches the selected landing, the down control valve closesslowly to decelerate the car to `leveling speed and when the'car islevel withV the landing the stop valve is closed to stop the car. Thissimple arrangement of a dashpot operated valve in a by-pass provides asmooth lacceleration and deceleration in the down direction.

A further feature resides inthe compact design of the valve system whichis located as a small unit adjacent the motor operated pump.

Another feature resides in a unique device for automatically operatingthe up and the down control valves according to the load in the car.This device, there being one for each of the two valves, includes adiaphragm l which is sensitive to line pressure and means operated bythe diaphragm to control. the degree of opening and of closing of thecontrol valve` and Athus to alter such openingfor various loadings tomake the leveling and' top-speeds uniform. Such pressure is aI functionof the elevator loading, `.the llow,` or volume ofhydraulic fluiddelivered to .the cylinder controllingV the speed ofthe elevator car.

A preferred embodiment of the inventionris illustrated I in theaccompanying drawings. t

In the drawings: p l Fig. Iv is a diagrammatic representation of ahydraulic elevator embodying the invention;

YTwo by-passes 'are provided inthe line;

between the pump 'and the cylinderfand` aty certain' times f in the.operation they returnhydr-aulicuid to a reservoirwhich supplies thepump. A control valve 'is located in eachof the `lay-passes4 and each ofthe valves is.pro

vided with'la dashpotso that it opens and closes slowly.

However, even whenffully closed, the valves lealfiluidI tothe reservoir.v

4 Upon thefregistration of any up startA sign-al, one. 'Off/the,

dashpot ,connected control valves, ie., theupjeontrol bfy-passedlthrough :the up.` control valve and returned to Y -the reservoir;` `.1l`hererbeingV only 20% of thetluid eiec- Fig. Il is an elevational viewof a subassrenibl-y of.v thel hydraulic elevator system with partsbroken awayI andl sectioned; v

Fig. llgl is a'plan 4view taken along thelirle` III- III4v of'Fig'. Il,certa'in'parts being shown insection; g

Fig. I'V' is an `elevational view as seen .froma-.position substantiallyalong ythe line IV--,IVl-of'Fig. IIII, -part:be-v

ing' shown in vertical section;

g'Fig. V is 'an elevationalfview a-s seen from aposition shown invertical section;y

control valveV shown incorporated in the subassembly in Fig. IV; and vFig; Vil is a schematic wiringV diagram of an electricalVV 1 jcontrolsystem-'forthe elevator.`v i ,f 'j

' These drawings and thefollowing description illustrate andi l:describeal preferred form 'of the Vinvention `but' 'are vnotintendedtolimit itsscope.

v.-;,Referringafa te Fig.y I, the hydraulie @avatar instar-'1 lation isone in which an elevator car 1, only a fragment of the floor of which isshown, is movable in a hatchway 2 between a oor 3 and another oorlocated at the level of the car 1 in its position shown. While onlyoperation between two landings will be described for the sake ofsimplicity, it is to be understood that the elevator may be arranged toserve more than two landings. The elevator car 1 is equipped with handoperated sliding gates or doors and the hatchway 2 is provided with alanding door at each floor; these doors are not shown since they areconventional. However, an example of conventional car doors and alanding door is shown and described in U.S. application Serial No.671,040, tiled on July 10, 1957 in the name of D. L. Baker, wherein thecar doors are so operatively and automatically connected to a landingdoor while the car is at a landing that such doors move together at thelanding.

The elevator car 1 is secured to the top of a lifting plunger or piston4 which extends downwardly into a cylinder 5 through a stuffing box 6.The cylinder 5 is connected to an oil reservoir 7 (Figs. II-V) by meansof piping 8, there being a positive displacement pump 9 connected in thepiping 8 between the cylinder 5 and the reservoir 7. A motor 10functions to drive the pump 9 and a pressure wave neutralizing unit 11connected in the piping 8 adjacent the pump 9 functions to substantiallyneutralize or eliminate pressure waves which are propagated from thepump. The unit 111 is shown and described in detail in U.S. applicationSerial No. 709,052, filed on January 15, 1958 in the name of I. H.Borden. The motor 10,l pump 9, neutralizing unit 11, and oil reservoir7, together with various control valving and interconnecting pipinghereinafter described, are suitably mounted in a frame 12 as shown inFig. II in the form of a compact subassemblage that can be fabricated inlots at a factory and carried in stock. The pump 9 is connected to thereservoir `7 by means of a conduit 13, a screen 14 in the reservoirstraining the oil before it flows by gravity from the reservoir which isunder atmospheric pressure to the pump.

The positive displacement pump 9 may be of any desired type butpreferably is of the type that is commonly known as a gear pump. Thepump when driven by the motor 10 takes oil or another suitable hydraulicmedium from the reservoir 7 and forces it through the unit 11 and piping8 to the hydraulic cylinder 5 which contains the lifting piston 4 thatis mechanically connected to the elevator car 1 tobe lifted. Thehydraulic lifting piston, the elevator car and the connectionstherebetween may be of any preferred existing type and they thereforeare not shown in detail in the drawings. 't

In the general operation of the elevator, assuming the car 1 is at floor3, upon the issuance of an up start signal after thedo'ors are closed,the car 1 starts'up slowly at leveling speed, `accelerates to top speedand Icontinues at top speedruntil a normaly open switch 15 (Fig. I)carried by they elevator car is closed by a stationary cam 16 secured inthe hatchway 2 and a :normally closed switch 17which is s tationarilymounted in the hatchway is opened -by a cam 18 that is carried by thecar, the switch 15 being closed just before the' switch 17 is opened.The cat '1f then starts to decelerate and continues in its upwardl pathuntilthe vroller of the normally open switch 15 rollsjoff of thestationary/"cam 16.A This stops the car. Should-the oar settle',l theswitch-15` again is closed, the hydraulic" pumpis actuated,` and thecaris moved upwardly at levellingspeed to a position level with thesec-@ad neer. whiiethe carts lever 'with the naar, the svlitch17` is heldopen by the cam' 18 as shown inFig. I.

. Upon-the issuance of a down start signal, the car starts down slowlyunder the'influjence of gravity at leveling Y speedwacceleratesto top.speedjand continues at top speedfluntilfa"normaly open switch 19Lcarried by the' arily mounted in the hatchway is opened by the cam 18that is carried by the car, the switch 19 being closed just before theswitch 21 is opened. The car then starts to decelerate and continues inits downward path until the roller of the normally open switch 19 rollsolf of the stationary cam 20. This stops the car. While the car is levelwith the Ioor, the switch 21 is held open by the cam 18.

The piping S is provided with two return by-passes or conduits each ofwhich includes a manifold 22. The left hand manifold 22 as viewed inFig. III leads to an up control valve 23 the lower end of which (Fig.11V) opens into the oil reservoir 7 and also leads to a relief valve 24which is a safety spring valve that is opened by excess pressure in thesystem to return oil from the piping 8 to the reservoir 7. Normally, therelief valve 24 remains closed. The right hand manifold as viewed inFig. III leads to an on or off stop valve 25 which communicates with adown control valve 26 the lower end of which (Fig. H) opens into the oilreservoir 7 and also leads to a hand operated valve 27 that functions torun the car down in case of power failure. Opening of the valve 27permits oil to ow from its lower end (Fig. II) into the reservoir 7.Normally, the valve 27 remains closed. A cover plate 28 on the reservoirkeeps the oil therein from splashing or bubbling out, there being tightfitting rings 29 around the valves 23, 24, 26 and 27 that rest ongaskets 3)V on the cover plate 28 at the respective openingstherethrough. Atmospheric pressure is maintained through an opening 31in the cover plate 28 at a splash guard 32 (Fig. Il) which is supportedby the cover late.

p During up travel, the stop valve 25, which is operated as hereinafterdescribed by a solenoid 33 (Fig. VII, line 210), is closed to isolatethe down control valve 26 from the system. Both of the control valves 23and 26 are so constructed and operated that they port when in closedposition. That is, when the up control valve 23 is fully closed and thepump 9 is operated, as an cxemplary figure only, 80% of the total flowat a check valve 34, which is located in the piping 8 between themanifolds 22, passes through the check valve 34 and 20% of the total owis bypassed through the up control valve 23 to the reservoir. When theup control valve 23 is fully opened and the pump 9 is operated, as anexemplary figure only, 20% of the total flow at the check valve 34passes through the check valve 34 and 80% of the total flow is divertedthrough the up control valve 23 to the reservoir.

During down travel, the check valve 34 isolates ythe up control valve 23fromthe system, the elevator car descending under the influence ofgravity with the motoroperated pump turned olf. Fluid flow is throughthe then opened solenoid stop valve -25 and the down control valve 26 tothe reservoir. When the down control valve 26 is fully closed, it allowsoil to leak into the reservoir in the same manner as the up controlvalve does. The control valves are identical except that the downcontrol valve '26 is normally closed while the up control valve 23 isnormally open. Hence, during up travel the failure of a solenoid35 (Fig.IV)l which operates the up control valve 23 does not prevent caroperation. That is, the

I n normally open up control'valve 23 'when' allowed to open because ofsolenoid failure only passes'about 80% of cariis closed by a stationarycam 20 secured in theihatch` Y way Zaanda normallygclosed 'switch 21'Awhich isstationthe total ow at the check valve 34 so that the car willstill loperate at slow or leveling speed when thev up control valve 23is fully open and when the pump 9 is operating. As in the up direction,thecar candescend at leveling speed under the influence of gravity evenwhen a solenoid 36- (Fig. V) which operatesv the -down control valve 26fails. Th'at is, the normally closed down control' valve "26wh`enallowed to closebecause of solenoid failure still leaks oil tothe'fres'ervoir so that thecar can descend'patleveling speedrf yMechanism for opening and closing the up control valve 23 slowly and foroperating the up control valve 23 according to the load in the car isillustrated in Fig. IV. The up control valve 23 includes a valvemanifold 37 which communicates with the manifold 22 and that supports alever pivot post 38 stationarily mounted thereon. An operating lever 39is pivoted at lll atop the post 38 and it is attached at its left end asviewed in Fig. IV to the plunger 41 of an oil lled dashpost 42 which ispivotally mounted to compensate for the arcuate move-v ment of the leverby means of a pin 43 on a bracket 4.4 fixed to the top of the manifold22, the. lever 39 being attached at its right end to a return spring 4Sthat has its lower end adjustably secured to a stationary bracket 46carried by the solenoid 35 which is carried in turn on a plate 47secured to the bottom of the valve manifold 37. A pair of small rightangle brackets 48` and 49 is pivotally mounted on the lever 39 by meansof pins 59 and 51 as spaced points intermediate the lever pivot il andthe returnspring 45. The armature of the .solenoid 35 is'operativelyconnected to bracket 49 by means of a pair of nuts 52 and a valveoperating rod 53 is connected to bracket i8l by means of a pair of nuts54, the brackets 48 and 49 being rockable `about the axes of the pins5t) and 51 to compensate for the arcuate motion of the lever 39 to whichthey are attached. Energizetion of the solenoid 35 causes the lever 3@to be pivoted in a counterclockwise direction about the pivot 4h asviewed in Fig. lV in opposition to the return spring d5. This lifts thevalve operating vrod 53, attached to the lever39, to close thenormallyopen up control valve 23, Upondeenergization of the solenoid,35, the return spring l5 pivotsthe lever 39 in a clockwise directionabout the pivot 4@ to reopen the normally open up control valve 23.

The up control valve 23 opensrand closes slowly because of the dampingeiect of the dashpot 62. This provides a smooth acceleration anddeceleration'on up travel, since the open up control valve 23, i.e., thecontrol valve in its levelingV speed position, by-passes perhaps 80% ofthe total ow at the check valve 3e to the reservoir 7 at the start ofthe up travel, leaving only 20% of the fluid effective for lifting `thecar, andro-loses slowly to produce more and more ilow ory volume offluid de-V livered to the cylinder and thus an'infnite number of speeds,whereby' a smooth acceleration in the up direction if obtained. Theamount of ow of the hydraulic fluid which is delevired to the cylindercontrols the speed of the car. Similarly, on approaching the selectedfloor slow opening of thev up control lvalve 23 leaks more and more oilto the reservoir`7 and the resulting lowery and lower flow to thecylinder" produces a smooth decelerationuntil the leveling speed isreached.

The degree of opening and of closing of the up con- 7 trol` valve 23 isaltered foryariousloadings through automatically adjustable rangesA tomake the leveling and ruiming speeds uniform'. This isy one of the moreimportant features of ythe elevator system and is accomplished by meansofa compensator diaphragm 55 in the form of an oil resisting cylindricalblock of flexible material that is so located inthe valve manifold-37that itis contacted along its bottom surfacebyoil at line pressure. Thediaphragm 55,".therefore, sensitive to the pressurein'the line whichpressure Jis a function of the loading offthe elevator `car l.`A"componeat'orv guide 56 is stationarily mounted in the valvemanifold37; it has a shoulder 57 and thevv'alve manifold 37 has an abuttingsurface 58 between which shoulder and surfacethe vcli-aphragm 55is'held. High line pressure causes the diaphragm S5 to be bowedupwardly-in a space 59 above the diaphragm-` "A cylindrical compensatorplunger 69" bears on the top of the cylindrical diaphragm 55 and lisconcentric therewith; it is slidable in a vertical hole that extendsthrough an "oversize hole in a stationary Y vvthrough the guide 56 andit carries a verticali'rod-61jy i v'valve sleeve 76 bears..

which is pivoted at its bifurcated end 65 at 66 to the post 38. Acompression return spring 67 surrounding the rod 6l is held between aspring seat 68 at its upper end and the upper end of the plunger, thespring seat 68 having an oversize hole through which the rod`6 extendsand being forced iby the spring 67 against the stationary springretainingplate 62 that is held in an adjustable position atop a pair ofadjustment bolts 69 threaded into the compensator` guide 56. Upwardmovement of the diaphragm is in opposition to the spring 67. Theselected positions of the bolts 69 are retained by means of locknuts 70.The sensitivity of the compensator diaphragm 55 is varied by compressingthe spring 67 more or less, i.e, the adjustable force applied by thespring 67 to the diaphragm SSthrough the plunger 6@ must be overcome bythe hydraulic force applied by the oil to the bottom of the diaphragmbefore the hydraulic force is able to bow the diaphragm upwardly andmove the plunger 60 and its attached rod 61 upwardly.

The valve operating rod 52'` extends through a hole 71 in thecompensator lever 64 and carries on either side of `the hole 71 a pairof stop nuts 72 which when they contact the lever 64 limit the amountthe up control valve 23- can be opened or closed. Since the position ofthe lever 66 is determinedby the hydraulic pressure upon the diaphragm55 to which it is operatively connected, i.le., movement ofthe diaphragmpivots the lever 64 about its pivot 66, when the nuts 72 Contact thelever 64 they limit the amount the up control valve 23- can be opened orclosed according to ythe line pressure and, hence, according to theloading of the car 1. Energiza-tion of the solenoid 35 causes the lever319 to be pivoted in ay counterclockwise direction `as viewed in Fig. IVabout the pivot Atti in opposition to the returnV spring 45 until thelower pair of the nuts 72 on the valve operating rod 53I connected tothe lever 39 contact the bottom ofthe compensator lever 64. This closesthe normally open up control valve 23` to an extent that is a functionof the car loading. Upon deenergization of the solenoid 35, the returnspring 45 pivots the lever 39 in' a clockwise direction about the pivot40 until the upper pair of the nuts 72 contact the top of thecompensator lever 64. This opens the normally open up'control valve 23Vlto an extent that is a functionof the car loading. The net result is anoperation lof the up control valve 23! in accorda.

horizontal roiwof equally spaced round holes 77 and a horizontal row,below the row of round holes y777, of equally spaced triangular holes 78is stationarily mounted concentrfically within the casing 73` by meanslof astrap 79 that is` Secured tol the ring 75 and upon which the Thevalve sleeve 76 Yextends through Vthe ring and fits therein with a tightt vto prevent leakage` of'oil.V An .elongatedvalve Vguide 80' having afoot 81 is Vstatioriarily mounted atop the valve sleeve 76m oill`sealedrelationship by` means of screws 8-2 and extends from its foot 81through :the casing 73 and through thewalvemanifold .37 in the form of as leeve and is held against movement transverse to its axis by means ofa tight ring 83 atop the valvernanifold: 37..

1 The valve operating rod 53 is located within the sleevel-ikevalveguide and it is secured at its lower end. to

the top of arvalve insert 84 which is slidably mounted within the sleeve7 6. The valveinsert `84 is provided with a relatively` wide anddeep'cirlcumferential groove 85,

averticalhole 86 along its axis, and' three equally spaced holesiljwhich lead fromithetop of thevalve insert at an angle -into the hole86, the holes 87 functioning as bleed passages that carry any oil whichleaks past the valve insert 84 to the vertical hole 86 in which it runsto the reservoir 7. Flow of oil is through the round holes 77 in thevalve sleeve 76 into the circumferential groove 85 in the valve insert84 and out of the triangular holes 78 in the valve sleeve 76 and downinto the reservoir 7, the pressure within the casing 73 being at linepressure and the pressure at the triangular holes 78 in the reservoirbeing at atmospheric pressure. As shown in Fig. Vl, all of thetriangular holes 78 are covered by the valve insert S4 except for asmall portion at the apex of each triangle. This is the closed positionofthe valve, i.e., even when closed the valve leaks oil to thereservoir. Slight downward movement of the valve insert 84 from itsposition shown in Fig. VI has its effect magnified by the fact that theareas of the triangular holes that are exposed to oil ow increaserapidly in a direction downward from the apex. Similarly, slight upwardmovement of the valve insert 84 has its effect magnified. Hence, thevalve is quite sensitive to any change in the range limits within whichit operates, i.e., the limits set automatically by means of the pressuresensitive cornpensator diaphragm 55.

It was found that a relatively large solenoid 35 was required to operatethe up control valve 23 insofar as it has been described. This wasdiscovered to result from a pressure reduction at 88 in the valve insert84 due to oil flow through the triangular holes 78. Hence, line pressureat 89l within the valve insert 84 overbalanced the reduced pressure at88. This pressurel difference had to be overcome by the solenoid. Thesystem is never sta-tic because the triangular holes 7S are nevercornpletely closed. If they were, then the force at 88 in a downwardvertical direction would exactly balance the force at 89l in the upwardvertical direction because line pressure would be imposed on each ofthese equal areas. The unbalance of forces due to the pressure dropinduced by tluid i'low across surface 88 is compensated for in the upcontrol valve 23y by means of a pin 90 which has an upper surface 91 andthat is arranged to slidein an opening through the foot 81 of the valveguide 80 and through an opening in a collar 92 that is stationarilymounted on the valve guide 80 as a guide for the pin 90. A stop 93 onthe guide 80'limits upwar'd travelof the pin 90. The pin 90 bears upon aspacer' 94 that "bears in `turn upon the upper end of the valve insert84 which isheld in place by means of the valve operating rod 53 thatpasses through an opening in the spacer 94. Force on the upper surface91 of the pin 90' adds to the downward force applied at 88 to the valveinsert 84 and so tends toward a balance of the forces in all directionson the valve insert 84 that the valve can be operated in eitherdirection with relatively little effort. Hence, the solenoid 35I can beof relatively small' siz'e.

"The control valves are identical except that the down controlv valve26'is normally closed while the up control valve 23 is normally open.Reference numbers in Figs. Il and V`which are applied to the downcontrol valve 26 vand which lare similar to those applied to the upcontrol valve 23'y identify similar parts. Mechanism for opening andclosing thedown control valve 26 slowly and for operatingthe'doWn-control valve 26 according to the load in the car isillustrated in Fig.v V. The down control valve' 26 includes a valvemanifold 95 which communicates with the stop valve 25 and that supportsa lever pivot post96 stationarily mounted thereon. An

- operating lever 97 is pivoted at 98 atop the post 96 and it isattached intermediate itsrends to the plunger 99 of anA oil filleddashpot 100 which is pivotally mounted to compensate forthe arcuatemovement of the lever by meansof a pin 101cm albracket 102 secured tothe top ofthe right hand end, as viewed in Fig. V, of a bracket 103which is secured in turn to the solenoid 36. A bracket 104 on the` lever97 serves to join the lever to 8 the top of the plunger 99. The solenoid36 is carried by a recumbent L-shaped bracket 'which is fixed to thevalve manifold 95. The lever 97 is attached at its left end to a returnspring 106 that has its lower end adjustably secured to the bracket 103on the solenoid 36.

A pair of small right angle brackets 107 and 103 is pivotally mounted onthe lever 97 by means of pins 109 and 110, the angle bracket 107 beinglocated at the right end of the lever and the angle bracket 108 beinglocated intermediate the return spring 106 and the dashpot 100. Thearmature of the solenoid 36 is operatively connected to bracket 108 bymeans of a pair of nuts 111 and the valve operating rod 53a is connectedto bracket 107 by means of a pair of nuts 112, the brackets 107 and 10Sbeing rockable about the axes of the pins 109 and 110 to compensate forthe arcuate motion of the lever 97 to which they are attached.Energization of the solenoid 36 causes the lever 97 to be pivoted in aclockwise direction about the pivot 98 as viewed in Fig. V in oppositionto the return spring 106. This lowers the valve operating rod 53a,attached to the right end of the lever 97, to open the normally closeddown control valve 26. Upon deenergization of the solenoid 35, thereturn spring 106 pivots the lever 97 in a counterclockwise directionabout the pivot 98 to reclose the normally closed down control valve 26.

The down control valve 26 opens and closes slowly because of the dampingeffect of the dashpot 100. This provides a smooth acceleration anddeceleration on down travel in the same manner as the dashpot 4-2 (Fig.IV) produces smooth acceleration and deceleration on up travel ashereinbefore described.

The degree of opening and of closing of the down control valve 216- isaltered for various loadings in the same way that the degree of openingand 0f closing of the up control valve 23 is altered as hereinbeforedescribed. Reference numbers in Fig. V which are applied to themechanism for operating the down control valve 26 according to the loadin the car and which are similar to those applied to identical mechanismshown in Fig. IV identify like parts.

With reference to Fig. VII, relays and all other circuit elements areshown in an across-the-line diagram. The relay contacts therefore areoften located remote from their actuating coils. In order to correlatethe location of the actuating coils and contacts, a marginal key hasbeen employed with the circuit diagram. With this key, the diagram hasbeen divided into horizontal bands which are identiiied with linenumbers in the right hand'margin. Relay symbols are located in themargin to the right of the linenumerals and in horizontal alignment withthe coil positions. The location of each contact actuated by 'a relaycoil is set forth to the right of the relay symbol in the key by thenumeral of the line upon which it appears. The numerals designating thelocation of back contacts, those which are normally closed when therelay is de-energized and are open when it is energized, are underlinedin the key to distinguish them from front contacts, those which areclosed upon theiractuating coil being energized. Thus, the time relayULT appearing in line 212 has a front contact at line 200 and a backcontact at line 202 as signified by the numerals inthe margin of Fig.yVH at line 212.

An operator` for example, who wishes to go to the second tioor entersthe car at the first iloor and closes theA car gate or door by hand, thecar gate being so operatively connected to the hall doors that the halldoors also close as hereinbefore described and operates a push button113 in line 216. Cams (not shown) lcarried by the gate and hall doorsmechanically close normally open switches 114 and 115 in a supply lead116. Current then flows from the supply lead 116 through the push button113, the energizing coil of a sealing relay S in line 216, the normallyclosed switch 17 in line 216 which is in the cuit to the motor .10, theiirst circuit to 9 v hatchway and which is held open by means of the cam18 on the car while the car is level with the second door, as shown inPig, I, the energizing coil of an up relayU in line 216,` and down relaycontacts D in line 216 to a return lead 121i. The sealing relay S inline 216 thereupon closes its contacts S in line 215 to provide asealing circuit around the push button 113 and the up relay U in line21:5 closes its contacts U in lines 219, 207, and 204, and opens .itscontacts U in lines 21S, 2115 and 210. y 'l The opening of the up relaycontacts U in line 21h insures that the energizing coil of a down relayD in line 218 cannot be energized accidentally at this time. The closingof the up relaycontacts U in line Zit/7 permits rectied current to ilowto the coil of the` up control valve solenoid 35 in line 2117, (also seeFig. 1V) and the normally open, dash-pot damped up control valve 23starts to close. The opening of the up relay contactsU .in line 205 cutsoff current flow to the energizing coil of a time relay DT in line 2115which was energized by current flow from the supply lead 116 upon theclosing of switches 114 and 115i. Deenergization yof the time relay DTcauses its normally closed contacts DT in line 2114 to close after abrief delay, Le., the time relay has a slow drop out. (hnrentA thenflows through the now closed timerelay contacts DT in line 21M and thenow closed up relay contacts U in line 2114 to the motor 1111 in line263 (alsosee Fig.A II). This starts the pump 9. The delay caused `by theslow drop out of the time relay DT in line 2115 allows the up controlvalve 23 to start to close before the. motor 11) starts. v

The closing of up relay contacts U in lin'e219` permits current to flowto the'energizing coil of .an auxiliary up relay lU1 in line 219. Theenergization of the auxiliaryv up relay U1 in line 219 causes it toclose its contacts U1 in lines 2 12 and 213; The closing of auxiliary uprelay contacts U1 in line 213 completes a circuit to the energizing coilof a retiring cam relay RS in line 213 and the closing of auxiliary uprelay contacts U1 in line 212 completes a circuit to the energizing coilof a time relay ULT in line 212. Energization ofthe retiring earn relayRC in line 213 causes its contacts RC in line 2111 to open and theenergization of the time relay ULT in line 212 causes its contacts ULTinline 20@ toclose and its contacts ULT in line 2112 to open.

The elevator car starts to movel upwardly as soon as i the motor startsat an increasing speed with a smooth acceleration until the up controlvalve 23 is fully closed and thus full speed is reached.` Asvthe carapproaches the second floor, the normally open switch 15 in" line 201(see also Fig. I) on the car is closed mechanically by the stationaryca1n'16 in the hatchway and shortly thereater the normally closed switch17` in -line216finzthe hatchway is opened by means of the cam 18 on 'theoar.

yThe closing of switch 15 in line 201 completes a circuit to theenergization coil of a leveling up' relayLU in line 2111, currentflowing through such coiland through time .relay contacts ULTin Vline21H1, Energization of the coil of the leveling uprela-y LU in line. 2111causes it to close its contactsLU in line 203 which completes a 4secondcirlthe motor 1@ being through the lead -at line 224, f j f The openingof switch 17 in line 216 opens the circuit to the up relay U in line 216and its contaotsU inlines 219, 218, 207,215, 204 and 2111 return toltheir original positions, i,e.,.theiripositions'shown in Fig. V11. Theopening of up relay' contacts U in line2ti'7 breaks the f circuit totheup control valve solenoid 35 in line 2197 and the normally open upcontrol valve 23 starts to open slowlyv and, therefore, the elevator carstarts to slow down with asmooth deceleration. The opening of up relaycontacts Uin line2t14 breaks therrst circuit to the motor 1i), the motorstill beingenergized,through; the circuit at line203;`y When the carisleveltwith the second door normally open switch 15. in line 261:opens-breaking the circuit to the leveling up relay yLU in line 2111and its contacts LU in line 203 open breaking the second circuit to themotor 10 and the car stops. In the up direction, there is no overrun ofthe car even with a light load, the car being operated at `slow orleveling speed just before it stops.

While the car is level with the second floor, switch v17 in line 216continues to be held open as illustrated in Fig. I. Should the carsettle slightly switch 15 in line 201 is closed again but switch 17 inline 216 continues to be held open to complete the circuit to theleveling up relay LU in line 2111 which then closes its contacts LU inline 203 to start. the motor 1u. This causes the car to be moved upwardat Slow or leveling speed because lat this point up control valvesolenoid 35 in line 207 is deenergized and the normally-open up controlvalve 23 is fully open. Whenthe vcaragain is level with the secondviloor, they normally open switch 15- in line 21.31 opens breaking thecircuit to the leveling up relay LU in line`2i1 and its contacts LU inline 2113 open breaking the circuit to the motor 10 and the car stopslevel with the floor.

As the car approached the second door, i.e., before the leveling upoperation, the closing of switch 15 in line 201 completed a circuit tothe energization coil of the leveling up relay LU in line 201, thecurrent flowing through such coil and through the time relay contactsULT in line 201i. However, in the levelingup oper-ation; the time relaycontacts ULT in line 2110 are open, since switch 17 in line 216 is heldopen at this time opening i RC in lineV 261 are closed, Since theretiring cam relay Y RC in line 213 is deenergized by the opening of theauxiliaryup relay contacts closing of switch 15 in line 221 completes acircuit to the energization coil of the leveling up relay LU in line2111 current lows through such coil and through the retiringcamfcontacts RC in line 2&1 to the ,return lead 120. Deenergization ofthe tirne relay ULT in line 212 causes its normally open contacts ULT inline 20%) and its normally closed contacts ULT in line 202 to open andclose, respectively, after a briet` delay,i.e., the time relay has aslow drop out. The delayed opening of the time Vrelay contacts VULT inline 21141 lassures lan unbroken circuit to the motor 10 at this time sothat there is 11o discon- Y tinuity in motor operation before theretiring cam con tacts RC in tline 201 drop in while stopping on the upVtrip. y t While only operationl between two landings has beendescribed, it is tobe understood that the elevator may be arrangedtoserve more than two landings.

To start down, a push button 141 in line 218 is' operated. When* gateand door contacts 111i and 115 are closed, current then flows fromVV thesupply lead 116 through the push button 141, the energizing ,coil ofavsealing relay S1 inline 218, normally closed switch 21 in line 218'which is in the hatchway and which is held open `by means of the cam 18on the car while the car is 'level 'with the iirstA floor, theenergizing coil of the down relay D in line 218, and the Vup relaycontactsuUl in line 218 to the return lead 1213. The sealing relay S1inline 218 thereupon `closes its contacts S1 in line 217 to provide asealing circuit aroundthe push button 141 and the down relay D in line218 opensV its contacts D in line 216 and closes 208, respectively. v

The-openingof the downrelay contacts D in line 216 l insures that theenergizing coil of thefup relay U in lineV U1 in line 213, and when theits contacts D in lines 214, 210 andl 216 cannot be energizedaccidentally at this time. The closing of the down relay contacts D inline 210 cornpletes a ycircuit to the coil of the stop valve solenoid 33in line 210 whereupon the stop valve 25 (Fi-g. III) opens. At the sametime, the closing of hte down valve contacts D in line 208 permitsrectified current to flow to the coil of the down control valve solenoid36 in line 208 and the normally-closed, dashpot-darnped down controlvalve 26 starts to open. The closing of the down valve contacts D inline 214 completes a circuit to the retiring cam relay RC in line 213which opens its contacts RC in line 201.

The elevator car starts to move down under the influence of gravity assoon as the stop valve 2S is opened at slow or leveling speed and, asthe down control valve 26 opens, at an increasing speed until full orrunning speed is reached` As the oar approaches the first iloor, thenormally open switch 19 inline 202 on the. car is closed mechanically bythe stationary cam 20 in the hatchway and shortly thereafter thenormally closed switch 21 in line 218 in the hatchway is opened'by meansof the cam 18 on the oar. The closing of switch'19 in line 202conditions a circuit to be completed to the energization coil of aleveling down relay LD in line 202 as soon as the retiring cam contactsRC in line 201 close. The opening of switch 21 in line 21S breaks thecircuit to the down relay D in line 218 and its contacts D in lines 216,214, 210 and 208 return to their original positions, i.e., theirpositions shown in Fig. VII. The opening of the down relay contacts D inline 268 opens the circuit to the coil of the down control valvesolenoid 36 in line 298 and the normally closed down control valve 26starts to close slowly. This causes a reduction in the speed of the 'carto the slow or leveling speed. At the same time,

the opening of the down relay contacts D in line 214A breaks the circuitto the retiring cam relay RC in line 213 and its normally closedcontacts RC in line 291 close to complete the circuit through the closedswitch 19 in line 202, the coil of the leveling down relay LD in line202, the time relay contacts ULT in line 202, and through the retiringcam contacts RC in line 219. Energization of the coil of the levelingdown relay LD in line 202 causes it to close its contacts LD in line 211to keep a circuit to the stop valve solenoid 33 closed even though thedown relay contacts D in line 210 are now open. When the car is levelwith the tirst oor, normally open switch 19 in line 202 opens lbreakingthe circuit to the leveling down relay LD in line 262 and its contactsLD in line 211 open breaking the circuit to the stop valve solenoid 33.The stop valve cioses and thus the car is stopped level with the rstfloor. v

It may be desirable under some circumstances to control the system bymeans of a single compensated control valve. Such a system includes,with reference to Fig. HI, the motor-operated pump 9, the normally opencontrol valve 23 in its by-pass to the reservoir, the check valve 34 andthe cylinder `S, i.e., the manifold 2,2 for the stop valve 25, the stopvalve 25 and the control valve 26 are eliminated from `the system. Inplace of such manifold 22, the stop valve 25 and the Vcontrol valvev2'6, a conduit from the cylinder to the control valve 23 is provided toby-pass the check valve 34, there being a solenoid operated o n or offvalve in the conduit. Alternatively, such manifold 22, the stop valve 2Sand the control valve 26 are eliminated and a solenoid operated check`valve which can be opened to permit flow of hydraulic medium from thecylinder to the control valve 23 issubstituted for the ordinary checkvalve 34. Y

To start up, the motor-operated pump is started 'and the normally opencontrol valve 23 which is open prior to the start up is closed slowly toproduce the acceleration, the check valve 34 and thesolenoid operated ouand olf valve in the conduit which lay-passes the check valve 34 orin-the alternative arrangement the solenoid operated check valve whichissubstituted for the ordioff valve in the bypass around the check valveto the control val-ve 23 or in the alternative arrangement through thesolenoid operated check valve which is substituted for the ordinarycheck valve 34 to the control valve 23. To stop on down travel, the nowopen control valve 23 is closed slowly to produce the deceleration andthe elevator car is stopped by closing the solenoid operated on and offvalve in the bypass around the check valve or in the alternativearrangement by closing the solenoid operated check valve which issubstituted for t-he ordinary check valve 34 to stop all ow of hydraulicmedium from the cylinder to lthe control valve 23.

It is to be understood that the foregoing detailed description is givenmerely by way of illustration and that many variations may be madetherein without departing from the spirit of the invention.

Having described the invention, I claim:

1. In a hydraulic elevator system, in combination, a hydraulic cylinder,a reservoir containing a hydraulic medium, conduit means connecting thecylinder and the reservoir, pumping mechanism in the conduit means fortransferring hydraulic medium from the reservoir to the cylinder toprovide elevator up travel, a first return conduit between the cylinderand the reservoir for returning hydraulic medium to the reservoir toprovide elevator down travel under the iniluence of gravity, a secondreturn conduit between the cylinder and the pumping mechanism forreturning hydraulic medium to the reservoir during elevator up travel,and a variable ow control valve operable 4through a continuous range ineach of the return conduits for controlling the ow of the hydraulicmedium through the return conduits and thus for controlling the flow ofthe hydraulic medium into and out of the cylinder.

2. In a hydraulic elevator system, in combination, a hydraulic cylinder,a reservoir containing a hydraulic medium, conduit means connecting thecylinder and the reservoir, pumping mechanism in .the conduit means fortransferring 4hydraulic medium from the reservoir to the cylinder toprovide elevator up travel, a rst return conduit between the cylinderand the reservoir for returning hydraulic medium to the reservoir toprovide elevator down travel under the influence of gravity, a secondreturn conduit between the cylinder and the pumping mechanism forreturning hydraulic medium to the reservoir during elevator up travel,variable tlow valve means in the return conduits for controlling the owof the hydraulic medium through the return conduits and thus forcontrolling the ow of the hydraulic medium into and out of the cylinder,and means, isolated from the hydraulic medium, for causing the valvemeans to open and close slowly providing controlled acceleration anddeceleration on up travel and on down travel.

3. In a hydraulic elevator system, in combination, a hydraulic cylinder,a reservoir containing ay hydraulic medium, conduit means connecting thecylinder and the reservoir, pumping mechanism in the conduit means fortransferring hydraulic medium from the reservoir'to the cylinder toprovide elevator up travel, a rst return conduit between the cylinderand the reservoir for returning hydraulic medium .to the'rcservoir toprovide elevator down travel under theinuence of gravity, a secondreturn conduit between the cylinder and the pumping mechanism forreturning hydraulic medium to the reservoir during elevator up travel,valve means in the return conduits for controlling the ilow of thehydraulic medium through the return conduits and thus for controllingthe flow of the hydraulic medium into and out of the cylinder, the valvemeans providing an adjustable ilow, and means sensitive to .the pressureof the hydraulic medium for adjusting the valve means to vary valverange limits according to various loadings of the elevator, wherebyuniform leveling and running speeds are provided.

4. In a hydraulic elevator system, 'in combination, a hydrauliccylinder, a reservoir containing a hydraulic medium, conduit meansconnecting the `cylinder and the reservoir, pumping mechanism in theconduit means for transferring hydraulic medium in forward now from thereservoir to the cylinder to provide elevator up travel, a first returnconduit between the cylinder and the reservoir for returning hydraulicmedium to the reservoir to provide elevator down travel under theiniiuance of gravity, a stop valve in the iirst return conduit forpreventing said return of hydraulic medium to the reservoir during.elevator up travel, a second return conduit between the cylinder andthe pumping mechanism for returning hydraulic medium to the reservoirduring elevator up travel, means in the hydraulic circuit for preventingbackward flow of hydraulic medium to the second return conduit, and acontrol valve in each ofthe return conduits for controlling the flow ofthe hydraulic medium through the lreturn conduits and thus forcontrolling the tlow of the hydraulic medium into andV out of thecylinder.

5. In a hydraulic elevator system, in combination, a hydraulic cylinder,a reservoir containing a hydraulic medium, conduit means connecting thecylinder and the reservoir, pumping mechanism in the conduit means fortransferring hydraulic medium in forward ilow from the reservoir tothe'cylinder to provide elevator up travel, a

iirst return conduit between the cylinder and the reservoir forreturning hydraulic medium to the reservoir to provide elevator downtravel under the influence of gravity, a stop valve in the trst returnconduit for preventing said return of hydraulic medium to the reservoirduring elevator up travel, a second return conduit between the cylinderand the pumping mechanism for returning hydraulic medium to thereservoir during elevator up travel, means in the hydraulic circuit forpreventing backward flow of 4hydraulicnredium to the second returnconduit, valve means in the return conduits for controlling the flow ofthe hydraulic medium through the return conduits and thus forcontrolling the flow of the hydraulic medium into and out of thecylinder, and means, isolated from the hydraulic medium, Iforretarding'l operation of the valve means to provide controlledacceleration and decelerationon 'up'travl and on down travel.V

6. In alhydraulic elevator system, in combination, a hydraulic cylinder,la reservoir containing a hydraulic inedium,'c0nduit means connectingthecylinder )and the reservoir, pumping mechanism in the conduit meanslfor transferring'hydraulic medium in forward flow from the lreservoirvtofthe cylinder to provide elevator up travel, a

first return conduit between the cylinder and the reservoir for`returning vhydraulic medium to thereservoir to provide elevator downtravel under the iniiuenceof gravity, a stop valvein thewrst returnconduit for-'preventing said return of :hydraulic medium to thereservoir during elevator uptravel, a second return conduit between thecylinder and the pumping mechanismtor returning hyhydraulic mediumdowntravel under means according to various loadings of the elevator,whereby uniform leveling and running speeds are provided.

7. In a control system for a hydraulic elevator having a hydrauliccylinder, in combination, variable flow valve means for controlling theow of a hydraulic medium into and out of the cylinder, and meanssensitive to the pressure of the hydraulic medium for controlling thedegree of opening and of closing of the valve means to vary valve rangelimits according to various loadings of the elevator. i

8.v In a control system for a'hydraulic elevator having a hydrauliccylinder, in combination, valve means for controlling the flow of ahydraulic medium into and out of the cylinder, the valve means operatingwithin range limits, and diaphragm means sensitive to the pressure ofthe hydraulic medium for adjusting the valve means to vary the rangelimits according to various loadings of the elevator.

9. In a control system for a hydraulic elevator having a hydrauliccylinder, in combination, adjustable stop means dening adjustablelimits, |valve means operable within a range between the adjustablelimits for controlling the flow of a hydraulic medium into and out ofthe cylinder, the degree of opening and of closing of the valve meansand thus the range limits being 4adjustable by adjusting the stop means,and diaphragm means sensitive to the pressure of the hydraulic mediumfor adjusting the stop means for various elevator loadings.

l0. In a control system for a hydraulic elevator having a hydratdiccylinder, in combination, variable flow valve means for controlling theflow of hydraulic medium into and out ofthe cylinder, and dashpot thehydraulic medium, operatively connected to the valve means for retardingthe opening and the closing of the valve means to provide controlledacceleration and deceleration on up travel and on down travel.

ll. In a control system for a hydraulic elevator having a hydrauliccylinder, in combination, an up control variabl-e flow valve forcontrolling the iow of a hydraulic medium into the cylinder, Ia downcontrol variable` flow valve for controlling the flow of the hydraulicmedium out of ythe cylinder, and a dashpot, isolated from thehyhydraulic medium, operatively connected to each of the valves `forretarding its opening'and closing to provide controlled acceleration anddeceleration on uptravel and on'` down travel.

l2. In a hydraulic elevator system, in combination, a hydrauliccylinder, a reservoir 'containing a hydraulic medium, conduit meansconnecting the cylinder and the reservoir, pumping mechanism in theconduit means `for transferring hydraulic medium `from the ,reservoir tothe cylinder to provide elevatorlup travel, a first return conduitbetween the cylinder and the reservoir for returning tothe reservoir toprovide elevator the influence of gravity, a second return conduitbetween the cylinder and the ypumping mechanism for returning hydraulicmedium'to the reserv voir duringjelevator'up travela'nd;a control valvein each draulic medium to the reservoir during elevator uptravel, f

means in the hydraulic circuit .for preventing backward flow ofhydraulic .medium tothe second return conduit, valvev means in thereturn .conduits for controlling the flow/of 'the hydraulicmedium;through the'return conduits `and thus foricontrolling the flow.of the hydraulic medium Vinto and out-o`f,thecylinder, the;valve meansproviding'an adjustable lrow, andrneans,` sensitive to the pressure ofthe hydraulic medium for adjusting the valve of the `return conduitsiior controlling'the flow ofthe hydraulicnrnedium through the returnconduits and thus for controlling the" flow of the hydraulic medium intoland out of the'c'ylinder, each of the control valves including a casingcommunicating with the respective return lconduiL-a sleeve stationarilymounted within the casing and` having inlet ports for receiving thehydraulic medium v under relatively high pressure from the casing andoutlet ports yfor dischargingthe hydraulic medium to the reservoir gatrelatively.; low .pressurefand an insert which is slidablyy,ountedjwithin thesleeve,v for'controlling the flow from the' outletports.

. 13. lna hydraulic elevator system,fn combination, a v

hydraulic cylinder, aV reservoir containin v a h draulicmedium,conduit'means connecting"thev cylinder andthe reservoir, pumpingmechanism in the conduit-means for means, isolated fromy transferringhydraulic medium from the reservoir to the cylinder to provide elevatorup travel, a iirst return conduit between the cylinder andthe reservoirfor returning hydraulic medium to the reservoir to provide elevator downtravel under the influence of gravity, a second return conduit betweenthe cylinder and the pumping mechanism for returning hydraulic medium tothe reservoir during elevator up travel, and a control valve in each ofthe return conduits for controlling the flow of the hydraulic mediumthrough the return conduits and thus for controlling the flow of thehydraulic medium into and out of the cylinder, each of the controlvalves including a casing communicating with the respective returnconduit, a sleeve stationarily mounted within the casing and havinginlet ports for receiving the hydraulic medium under relatively highpressure from the casing and outlet ports for discharging the hydraulicmedium to the reservoir at relatively low pressure, an insert which isslidably mounted within the sleeve for controlling the flow from theoutlet ports, and means tending -to balance the forces on the inserteven though it experiences a pressure drop adjacent the outlet ports.

14. In a hydraulic elevator system, in combination, a hydrauliccylinder, a reservoir containing a hydraulic medium, conduit meansconnecting the cylinder and the reservoir, pumping mechanism in theconduit means for transferring hydraulic medium in forward ow from thereservoir to the cylinder to provide elevator up travel, a lirst returnconduit between the cylinder and the reservoir for returning hydraulicmedium to the reservoir to provide elevator down travel under theinfluence of gravity, a stop valve in the rst return conduit forpreventing said return of hydraulic medium to the reservoir duringelevator up travel, a second return conduit between the cylinder and thepumping mechanism for returning hydraulic medium to the reservoir duringelevator up travel, means in the hydraulic circuit for preventingbackward ow of hydraulic medium to the second return conduit, and acontrol valve in each of the return conduits for controlling the iiow oft-he hydraulic medium through the return conduits and thus forcontrolling the flow of the hydraulic medium into and out of thecylinder, each of the control valves including a casing communieatingwith the respective return conduit, a sleeve stationarily mounted withinthe casing and having inlet ports for receiving'the hydraulic mediumunder vrelatively high pressure from the casing and outlet ports fordischarging the hydraulic medium to the reservoir at relatively lowpressure and an inseit which is slidably' mounted within the sleeve forcontrolling the -ilow from the outlet ports.

l5. In a hydraulic elevator system, in combination, a hydrauliccylinder, a reservoir containing a hydraulic medium, conduit meansconnecting the cylinder and the reservoir, pumping mechanism inl theconduit means for transferring hydraulic medium in forward flow from thereservoir to the cylinder to provide elevator up travel, a rst returnconduit between the cylinder and the reservoir for returning hydraulicmedium to the reservoir to provide elevator .down travel under theinfluence of gravity, a stop valve in the first return conduit forpreventing said return of hydraulic medium to the reservoir duringelevator up travel, a `second return Vconduit between the cylinder andthe pumping mechanismv for returning hydraulic medium to the reservoirduring elevator up travel, means in the hydraulic circuit for preventingbackward ow of hydraulic medium to the second return conduit, and acontrol valve in each of thereturn conduits for controlling the flow ofthe hydraulic medium through the return conduits and thus forcontrolling the llow ofthe hydraulic medium. into and out of thecylinder, each of the control valves including a casing communicatingwith the respective return conduit, a

sleeve stationarily mounted within the casing and having inlet ports`for receiving the hydraulic medium under relatively high pressure fromthe casing and outlet ports for discharging the hydraulic medium to thereservoir at relatively low pressure, an insert which is slidablymounted within the sleeve for controlling the flow from the outletports, and means tending to balance the forces on the insert even thoughit experiences a pressure drop adjacent the outlet ports.

16. A hydraulic elevator system comprising, in combination, loadcarrying means, a plunger operatively connected to the load carryingmeans, a hydraulic cylinder for the plunger, a reservoir containing ahydraulic medium, conduit means connecting the cylinder and thereservoir, pumping mechanism in the conduit means for transferringhydraulic medium from the reservoir t0 the cylinder to provide elevatorup travel, means for causing operation of the pumping mechanism to raisethe load carrying means, up control valve means operable at the start ofthe pumping mechanism to cause acceleration of the load carrying meansand operable as the load carrying means nears a selected level to causedeceleration of the load carrying means to a leveling speed, means forstopping the pumping mechanism and thus the load carrying means when theload carrying means becomes level with the selected level, a returnconduit located between the cylinder and the reservoir for returninghydraulic medium to the reservoir to provide elevator down travel underthe inuence of gravity, a stop valve in the return conduit which isclosed during up travel, means for causing the opening of the stop valveto lower the load carrying means, a down control valve in the returnconduit operable at the opening of the stop valve to cause accelerationof the load carrying means and operable as the load carrying means nearsa selected level to cause deceleration of the load carrying means to alleveling speed, and means for closing the stop valve and thus forstopping the load carrying means when the load carrying means becomeslevel with the selected level.

17. A hydraulic elevator system according to claim 16 wherein the meansfor stopping the pumping mechanism and thus the load carrying means whenthe load carrying means' becomes level with the selected level functionsadditionally to restart the pumping mechanism to raise the load carryingmeans at leveling speed should the stopped load carrying. means settlebelow the selected level and again stops the pumping mechanism and .thusthe load carrying means when the load carrying means becomes level withthe selected level. I 18. A hydraulic elevator system according to.claim 16 wherein delay means are provided to permit operation of the upcontrol valve means to start before operation of the pumping mechanismbegins on up travel.

19. A hydraulic elevator system according to claim 16 wherein the -upcontrol valve means includes a by-pass located between thecylinder andthe pumping mechanism for returning hydraulic medium to the reservoirduring up ltravel and an up control valve in' the by-pass forcontrolling the flow of the hydraulic medium through the by-pass andthus for controlling the ow of the hydraulic medium into the cylinder. A

Y20. A hydraulic elevator systemaccording to claim 16 wherein theacceleration and deceleration provided by the up control valve means andby the down control valve is caused by jdashpot means isolated from thehydraulic medium and operatively connected to the-up control valve meansand to the down control valve whereby they open and close slowly.

2l. A hydraulic elevator system according to claim 16 wherein means areprovided which are sensitive to the pressure of the hydraulic medium inthe conduit means for controlling the degree of opening and of closingof the up control valve means and thedown control'valve according tovarious loadings of the load carrying means, whereby uniform levelingand running speeds forl various loadings are obtained.A .if 22. Ahydraulic elevator System according'to claim 17 19 wherein both of thecontrol valves leak hydraulic medium to the reservoir even when suchvalves are closed.

23. A hydraulic elevatorsystem according to claim 22 wherein each of thecontrol valves provides an adjustable leakage to the reservoir. v

24. A hydraulic elevator system according to claim 23 wherein diaphragmmeans are provided which are sensitive to the pressure of the hydraulicmedium in the conduit means for adjusting the control valvesautomatically according to various loadings of the load carrying means.

l25. A hydraulic elevator system comprising, in combination, loadcarrying means, a plunger operatively connected to the load carryingmeans, a hydraulic cylinder for the plunger, a reservoir containing ahydraulic medium, conduit means connecting the cylinder and thereservoir, pumping mechanism in the conduit means for transferringhydraulic medium from the reservoir to the cylinder to provide elevatorup travel, means for causing operation of the pumping mechanism to raisethe load carrying means, up control valve means` for controlling the owof the hydraulic medium into the cylinder operable at the start of the.pumping mechanism to cause acceleration of the load carrying means andoperable as the load carrying means nears a selected level to causedeceleration of the load carrying means to a leveling speed, means forstopping the pumping mechanism and thus the load carrying means when theload carrying means becomes level with the selected level, means forreturning hydraulic medium to the reservoir to provide elevator downtravel under the influence of gravity, down control valve means forcontrolling the iiow of the hydraulic medium out of the cylinderoperable at the start of the elevator down travel to cause accelerationof the load carrying rneans and operable as the load carrying meansnears a selected level to cause deceleration of the load carrying meansto a leveling speed, and means for stopping said return of hydraulicmedium to the reservoir to stop the load carrying means when the loadcarrying means becomes level with the Selected level.

26. A hydraulic elevator system according to claim 25 wherein the meansfor stopping the pumping mechanism and thus the load carrying means whenthe load carrying means becomes level with the selected level functionsadditionally to restart the pumping mechanism to raise the load carryingmeans at leveling speed should the stopped load carrying means settlebelow the selected level and again stops the pumping mechanism and thusthe load carrying means when the load carrying means becomes level withthe selected level.

27. A hydraulic elevator system according to claim 25 wherein delaymeans are provided to permit operation of the up control valve means tostart before operation of the pumping mechanism begins on up travel.

28. A hydraulic elevator system according to claim 25 wherein the upcontrol valve means includes a bypass located between the cylinder andthe pumping mechanism for returning hydraulic` medium to the reservoirduring up travel and an up control valve in the by-pass for controllingthe flow ofthe hydraulic medium through the by-pass and thus forcontrolling the llow of the hydraulic medium into the cylinder.

29. A hydraulic elevator system according to claim 25 18 wherein theacceleration and deceleration provided by the control valve means iscaused by damping means, isolated from the hydraulic medium, operativelyconnected to the valve means for slow operation of the valve means.

30. A hydraulic elevator system according to claim 25 wherein diaphragmmeans are provided which are sensitive to the pressure of the hydraulicmedium in the conduit means for controlling the operation of the controlvalve means according to load upon the load carrying means, wherebyuniform leveling and running speeds for various loadings are obtained.

31. A hydraulic elevator system according to claim 25 wherein both ofthe control valve means leak hydraulic medium to the reservoir even whensuch valve means are closed.

32. A hydraulic elevator system according to claim 31 wherein each ofthe control valve means provides an adjustable leakage to the reservoir.

33. A hydraulic elevator system according to claim 32 whereincompensator means are provided which are sensitive to the pressure ofthe hydraulic medium in the conduit means for adjusting the controlvalve means automatically according to various loadings of the loadcarrying means.

34. In a control system for a hydraulic elevator having a hydrauliccylinder which is supplied with a hydraulic medium, in combination,valve means including at least one valve for controlling the ow of thehydraulic medium into and out of the cylinder, a valve operating rod foropening and closingfthe valve and valve stop means carried by the rod,compensator stop means movably mounted adjacent the valve stop means,means for moving the valve operating rod until the valve stop meanscontacts the compensator stop means, and compensator means sensitive tothe pressure of the hydraulic medium `for positioning the compensatorstop means according to such pressure and thereby controllingautomatically the degree of opening and of closing of the valveaccording to various loadings of the elevator.

35. A control systemfor a hydraulic elevator according to claim 34wherein a dashpot is connected to the means for moving the valveoperating rod, whereby the valve is opened and closed slowly.

36. A control system for a hydraulic elevator according to claim 34wherein the compensator means includes a diaphragm.

37. A control system for a hydraulic elevator according to claim 34wherein the compensator means includes a diaphragm, a plunger that isoperatively connected to the compensator stop and that is driven in onedirection by the diaphragm, and a return spring for drivng the plungerin a return direction. 38. A control system for a hydraulic elevatoraccording to claim 37 wherein means are provided to adjustably prestressthe return springl to vary the sensitivity of the diaphragm.

References Cited in the le of this patent UNITED STATES PATENTS

